Time-delayed control device



July 2 w. M. zmcss ET AL I 3,4

TIME-DELAYED CONTROL DEVICE I Filed Feb. 20, 1968 v 2 Sheets-Sheet 1 INVENTORS. Warren M 2/099 BY Pau/R .Swf/Y HTTORNEV July 22, 1969 w, M. ZlNGG. ET AL 3,457,431

TIME-DELAYED CONTROL DEVICE Filed Feb. 20, 1968 2 Sheets-Sheet 2 INVENTORS. Warren M Z 1099 United States Patent US. Cl. 307-116 4 Claims ABSTRACT OF THE DISCLOSURE A time-delayed detonating device which comprises: a hollow fluid impervious pressure resistant housing consisting of at least two detachable units. One unit consists of a cup-shaped housing having a spring action arming mechanism mounted therein. The second unit consists of a cylindrical shaped housing having an inner support member constructed of an electrical insulating material. Mounted on the inner support member in appropriate electrical connection is an arming switch positioned so as to be activated by said arming mechanism, a timing device, a firing switch, a self-contained power source and a pair of terminals extending outside said housing for connecting the leads from an initiator. The device is useful for detonating explosives employed under elevated pres sures and in the presence of electrical conductive fluids such as those encountered in underground oil and gas formations.

Background Oil and gas wells are frequently treated to increase the production of oil and gas by fracturing the underground formation. A commonly employed method consists of pumping an ammonium nitrate based slurry explosive into a wellbore, forcing the slurry into oil or gas bearing formations and then detonating the explosive. Various detonation devices and initiators have been employed for detonating the explosive charge, including, for example, shaped charges which are detonated by time-delay type detonators or initiated by electrical cable means coupled to a suitable control unit disposed near the wellhead. The use of electrical cables can be dangerous if careful safety precautions are not taken. Also, the various time-delay detonating devices employed have caused problems because of the dangers involved in arming them and premature detonation in a well because of shorting out due to the presence of electrical conductive fluids. Conversely, many have failed to detonate because of the harmful effect of the high pressures encountered at the great depths and under the high hydrostatic heads commonly encountered in such wells. The present invention, through a novel combination of safety and arming mechanisms, eliminates substantially all the disadvantages associated with presently employed time-delayed detonating devices.

Summary The present time-delayed detonating device consists of a separable fluid impervious pressure resistant housing which is divided into at least two detachable units. One unit contains a spring-action arming mechanism which is armed after the device has been placed in a position in a well. The second unit contains an inner support member constructed of an electrical insulating material and on which is mounted, in an appropriate electrical circuitry, an arming switch, power source, timing device, firing switch and terminals for connecting a blasting cap or the like. The arming switch is positioned to be activated by the spring-action arming mechanism. Also, a third hollow housing, in which a blasting cap and an explosive booster may be positioned and connected to the electrical terminals, may be incorporated in the present device. The units have mating joints which, when fitted together, provide a liquid impervious hollow pressure resistant structure containing the arming and detonating mechanisms.

Drawings FIGURE 1 represents a side elevation, partly in section, of one embodiment of a detonating device of the present invention consisting of three housings securely fitted together and with the arming mechanism in an unarmed position.

FIGURE 2 represents a side elevation, partly in section, of one embodiment of an arming mechanism as shown in FIGURE 1 with the arming pin in an upper unarmed position.

FIGURE 3 represents a side elevation, partly in section, of the embodiment of the arming mechanism as shown in FIGURES 1 and 2 and with the arming pin in a lower armed position, closing an arming switch.

FIGURE 4 represents an isometric view, partly in section, of the arming mechanism and showing the trigger and arming pin in alternative positions.

Preferred embodiments One embodiment of the present detonating device is depicted in the figures and consists of an elongated hollow fluid impervious pressure resistant support member 70 having an upper cup-shaped housing 11, containing a spring-action arming mechanism 12; a middle housing 13, removably attached to said upper housing and containing a power source 14 and a timing device 15; and including a lower housing 16 removably attached to the middle housing and wherein an initiator and booster can be placed. The lower housing 16 although optional is usually preferred. The detonator is characterized in that it contains several safety features which substantially eliminate any chance of premature detonation. Also, the detonator is characterized in that when the housings are in a jointed and mated position, as shown in FIGURE 1, they provide a substantially fluid impervious pressure resistant structure which can be employed in oil wells and other like fluid bearing mediums containing electrical conductive fluids.

One embodiment of a spring-action arming mechanism 12 is depicted in the figures. This mechanism comprises an elongated arming pin 17 having an elongated lower portion 18; an elongated upper portion 19; a stroke limiting member 20 positioned intermediate said lower and upper portions so as to restrict the downward movement of the pin, and a beveled notch 21, having a slanted seat 22, positioned in the upper portion 19 above the stroke limiting member 20. The elongated upper portion 19 of the pin 17 is slidably engaged through a guide port 23 in a support member 24 and extends therethrough. A coil spring 25, or other suitable biasing means, is positioned onto pin 17 intermediate the stroke limiting member 20 and the lower face 26 of the support member 24 and tends to force the elongated arming pin 17 down and through the port 23 in the support member 24. An upward stroke limiting restraint 27 can be positioned on the upper elongated portion 19 of the pin 17 intermediate the stroke limiting member 20 and contacts the lower face 26 of support 24 to limit the upper movement of the pin. A trigger 28, generally elongated in shape and containing a beveled notch 29 having a slanted seat 30, FIGURES 2, 3 and 4 which mates with the slanted seat 22 in the beveled notch 21 on the arming pin 17, is pivotally attached to the upper face 31 of the support member 24. When the trigger is maintained in a closed position, as depicted in FIGURE 2, and the pin 17 is in an unarmed upper position as shown, the slanted seat 22 of the notch 21 in the pin 17 mates with the slanted seat 30 in the trigger 28, the spring 25 is compressed, and the arming pin 17 is restrained from being lowered into an armed position. The trigger usually is prevented from pivotal movement when the arming mechanism is in an unarmed state, i.e. the arming pin 17 is in an upper position, FIGURES 1 and 2 by a restraining means. Conveniently the restraining means consists of a safety pin 32 which is inserted through a port 33 in the end of the trigger opposite to the pivoted end and into a corresponding port 34 in the support member 24. The angle of the slope of the two seats 22 and 30 and the compression strength of the spring 25 are such that when the safety pin 32 is withdrawn the trigger will be forced away from the pin thereby allowing the pin to be forced into a lower armed position. The arming mechanism is usually removably secured in the upper housing 11 by suitable securing means 35, e.g., one or more set screws which engage the support member 24. The lower elongated portion 18 of the arming pin 17 extends through a guide port 36 in the bottom portion 37 of the upper housing 11. The lower elongated portion 18 also usually contains at least one O-ring gasket sealer 38 to provide a fluid tight seal between the upper chamber 39 and lower face 40 of the upper housing 11. Other specific arming mechanisms which may be armed after being placed in a borehole of a well may be employed in the present device without departing from the present invention.

The middle housing 13 of the detonator contains a removable inner support member 41 which is constructed of an electrical insulating material. The upper end of the inner member 41 is usually removably attached to the lower face 40 of the upper housing 11 and contains a port 42 matching the port 36 in the lower portion of the housing 11. A portion of the wall of the inner support member 41, usually conforms substantially in shape to the inner wall of the middle housing and fits snugly therewith when mounted in place. The lower end of the inner support 41 and lower end of the middle housing may be designed so as to form a liquid tight seal with the terminals 45 and 49 being exposed on the exterior of the housing 13. In this manned even if a lower housing 16 is not employed, the inner chamber 43 of the middle housing will be substantially impervous to fluids.

An arming switch 44, e.g., a micro safety switch, is mounted on the inner support member 41 directly opposite to the ports 36 and 42 and the lower portion 18 of the arming pin 17 and is urged intoa closed position, FIGURE 3, when the arming pin is in a lower armed position.

The arming switch 44 is electrically connected to the self-contained power source 14, e.g., a size D flashlight battery, and one electrical terminal 45, usually mounted through the lower end of said inner support member, for

attaching a lead 46 from a blasting cap 47 or other initiator. The power source 14 is also electrically connected to one terminal of a firing switch 48 which is activated by the timing device 15. The other terminal of the firing switch 48 is electrically connected to a second terminal 49 to which is attached a second lead 50 from the blasting cap 47. The terminals 45 and 49 are fitted through the lower end of the inner support so as to provide a liquid tight joint and usually only the outer jacks of the'terminals are exposed outside the inner chamber of the middle housing. When the arming switch 44 and firing switch 48 are in a closed position an electrical circuit is made between the power source 14 and the two ter-' minals 45 and 49. However, no electrical circuit can be completed prior to the removal of the safety pin and the closing of the arming switch. Thus, even if a malfunction occurs in the timing device, the initiator cannot be detonated until the safety pin has been removed which preferably does not occur until the device is placed below the surface and into the formation to be fractured.

As indicated, a lower housing 16 also may be employed and usually consists of a hollow body in which an initiator such as the blasting cap 47 may be placed and attached to the terminals 45 and 49 and to suitable boosters.

The housings of the detonator are fitted together so as to provide a continuous fluid tight, generally elongated pressure resistant housing. For example, the upper housing, middle housing and lower housing can be fitted together by employing tightly fitting overlapping joints 51 and made substantially fluid tight by the use of one or more O-rings 52 at each joint. The joints are secured in the overlapping mating position by the use of set screws 53 or secured by other means, e.g., mating threaded joints, to assure an essentially solid fluid impervious structure.

In a further embodiment a second safety pin 54 is pivotly attached to the arming pin 17, usually on the stroke limiting member 20. The second safety pin is of such a length that the end of the pin extends through a port 55 provided in the wall of the upper housing 11. When the middle housing 13 is not attached to the upper housing and when the arming pin 17 is in an armed position, FIGURE 3, the pin extends through and protrudes outside the wall of the upper housing. The protrusion of the pin through the wall of the upper housing prevents the middle housing and upper housing 11 and 13 from being fitted together. However, when the arming pin is in an unarmed position the second safety pin 54 is withdrawn from the port 55 and the two housings can be fitted together. The pin is usually constructed of a readily pliable material, e.g., soft wire, so that it will not restrict the downward movement of the arming pin after the detonator has been completely assembled. The pin need only be strong enough to prevent the middle housing from being fitted to the upper housing when the arming pin is in a lower armed position. Thus the inclusion of the second safety pin 54 prevents the assembly of the detonator when the arming pin is in an armed position and thus prevents the chance of a premature detonation.

For ease of construction and adaptability for forming watertight joints, the housings are usually provided in cylindrical shapes. They may be constructed of any materials, e.g., aluminum, which are sufficiently strong to withstand the pressures encountered in use. When the detonator is to be used under exceedingly high pressures it may be constructed of steel or another sufliciently strong material.

The inner support member 41 is constructed of an electrical insulating material; for example, various nonconducting synthetic plastic materials are appropriate.

The blasting cap and boosters will depend on the nature of the explosive to be detonated. The selection of a particular detonator for use in a given operation readily is apparent to those skilled in the art.

The power source usually consists of a dry cell battery. A heavy-duty size D flashlight cell is usually appropriate for most uses.

The timing device 15 consists of any timing mechanism which can be preset to close the firing switch 43 after a predetermined period of time.

In operation the detonating device is separated into its various housings. The arming pin 17 is positioned in an upper unarmed position and restrained in this unarmed position by closing the trigger 28 and placing the first safety pin 32 in position to restrain the trigger. The timing device 15 is then set to activate the firing switch 48 after a predetermined period of time. Because of the unique design of the present device even if the firing switch is activated prematurely, an electrical circuit is not made between the power source and first and second terminals until the safety pin 32 has been removed and the arming switch 44 is closed. The upper and middle housings are then assembled and an appropriate size blasting cap is connected to the terminals and to a booster., e.g., shaped charge. As indicated, a lower housing 16 can also be employed if desired. The detonator is lowered into the wellbore to be fractured, e.g., by lowering it in a bailer, and armed for firing by withdrawing the first safety pin by means of a suitable line attached thereto. The detonation of the blasting cap initiates the booster which in turn shatters the lower housing and detonates an explosive charge. Several of the detonating devices may be placed at predetermined distances along a column of explosive and timed to detonate simultaneously or at predetermined time lags as desired.

Various modifications may be made in the present invention without departing from the spirit or scope thereof for it is understood that we are limited only as defined in the appended claims.

What is claimed is:

1. A time-delayed control device which comprises:

(a) an elongated hollow substantially fluid impervious pressure resistant support member comprising at least an upper cup-shaped housing having a solid bottom portion with a port substantially centered therethrough, and including a joint about the periphery of said bottom portion, and a lower substantially cylindrical shaped housing having a joint about the periphery of the upper end of said lower housing which mates with the joint in said upper housing to form a solid and substantially fluid impervious seal;

(b) a spring action arming mechanism supported in said upper housing having an arming pin slidably engaged through said port in said upper housing and moveable by said spring action to an upper and lower position;

(c) an inner support member removably positioned in said lower housing and having a joint about the lower portion thereof to form a fluid impervious joint with the lower portion of said lower housing and further characterized by being constructed of an electrically insulating material;

(d) a self-contained power source mounted on said inner support member;

(e) an arming switch electrically connected to said power source and positioned on said inner support member opposite to the arming pin so as to be urged into a closed position when said arming pin is in a lower position;

(f) a timing device electrically connected to said power supply;

(g) a first terminal mounted through the lower portion of said inner support member and connected to said arming switch; and

(h) a second terminal mounted through said lower portion of said inner support member and electrically connected to said timing device, said first and second terminals being provided for electrical connection of an initiator to the timing device.

2. The time-delay control device as defined in claim 1 wherein said arming mechanism comprises:

(a) a support member mounted in said upper housing and having a guide port centrally positioned therein 5 and having an upper and a lower face;

(b) an elongated arming pin having an elongated lower portion, an elongated upper portion, a stroke limiting member positioned intermediate said upper and lower portions and a beveled notch having a slanted seat positioned in said upper portion, said upper portion slidably engaged through said port in said support member and said lower portion being slidably engaged through said port in said upper housing;

face of the support member; and

(d) a trigger pivotally mounted on said support member, having a slanted seat matching the slanted seat in said upper portion of the arming pin to maintain the arming pin in an upper position and containing a safety pin to activate said trigger.

3. The time-delayed control device as defined in claim 2 including in addition:

(a) a second safety pin mounted on said arming pin, said pin being of such a length that it extends through and protrudes from a port positioned in the wall in the lower portion of the upper housing which forms said joint when said arming pin is in a lower position and said lower housing is not attached to the upper housing.

4. The time-delayed control device as defined in claim 1 including in addition:

(a) a third hollow housing having one open end and VOLODYMYR Y. MAYEWSKY, Primary Examiner US. Cl. X.R.

(c) a coil spring positioned onto the arming pin intermediate said stroke limiting member and said lower 

